The present invention generally relates to a terminal arrangement for an SMD-capable hybrid circuit.
Hybrid or film circuits are electronic subassemblies in which planar interconnect structures and passive elements, especially resistors, are placed onto a ceramic substrate by means of a special film or layer technology. These planar structures are connected, or respectively, hybridized on the common ceramic substrate with other elements, e.g. IC's or relays. These other elements are commonly surface-assemblable; that is, in the known SMD (surface mounted devices) technology, they are placed onto terminal spots on the hybrid circuit and soldered there, mostly by reflow soldering.
In the course of lowering the production and assembly outlay in the production of printed circuit boards, a complete transition to surface assembly technology is desired. Therefore, the hybrid circuit as a whole should itself in turn be SMD-capable. To be sure, in order to obtain a high integration density, hybrid circuits today are mostly soldered in as single in-line subassemblies in printed circuit boards. In order to exploit the space provided in the third dimension, they are assembled perpendicular to the printed circuit board, or respectively, of the substrate, with only one row of terminals. However, to the present day, single in-line hybrid assemblies are connected with the mother board (substrate) exclusively by means of a plug-in assembly and are meanwhile nearly the last element which cannot be incorporated into SMD technology.
Problems in the realization of perpendicularly assembled SMD-capable hybrid assemblies lie primarily in the planarity requirement of the terminal pin, e.g. a co-planarity of 0.1 mm is required given a solder paste pressure of 0.15 mm in thickness but also in mechanical demands on the terminal pins with reference to swinging 9 or swivelling or pivoting and pushing stress in the device, particularly during transport. Besides this, from a design standpoint, the hybrid circuit itself must withstand the increased stresses in the SMD assembly, and this should not, of course, require any increased production outlay as far as possible, e.g. additional safety measures during soldering.